Camera Raw curves as Photoshop's: the fitted parametric curve, the tone curve on each channel, one drag in the graph (13.18)

src/UI/CameraRawColorControls+Curve.cpp

@@ -0,0 +1,114 @@
+#include "UI/CameraRawColorControls.h"
+#include <algorithm>
+#include <array>
+#include <cmath>
+
+// Swift's curve graph drags, picked once at the press.
+std::optional<CameraRawCurveControls::Drag> CameraRawCurveControls::parametricDrag(QPointF at, QSizeF size) const
+{
+    const CameraRawCurveSettings curve = raw().curve;
+    const double tone = at.x() / std::max(size.width(), 1.0) * 100;
+    const std::array<double, 3> splits{curve.shadowSplit, curve.darkSplit, curve.lightSplit};
+    // Along the bottom, the nearest divider, the first of equals.
+    if (at.y() > size.height() - 18) {
+        size_t nearest = 0;
+        for (size_t index = 1; index < splits.size(); ++index)
+            if (std::abs(splits[index] - tone) < std::abs(splits[nearest] - tone))
+                nearest = index;
+        return Drag{.kind = Drag::Kind::divider, .index = nearest, .from = at};
+    }
+    double CameraRawCurveSettings::*key = tone < splits[0]   ? &CameraRawCurveSettings::shadows
+                                          : tone < splits[1] ? &CameraRawCurveSettings::darks
+                                          : tone < splits[2] ? &CameraRawCurveSettings::lights
+                                                             : &CameraRawCurveSettings::highlights;
+    return Drag{.kind = Drag::Kind::region, .key = key, .start = curve.*key, .from = at};
+}
+
+std::optional<CameraRawCurveControls::Drag> CameraRawCurveControls::pointDrag(QPointF at, QSizeF size)
+{
+    const double x = at.x() / std::max(size.width(), 1.0), y = 1 - at.y() / std::max(size.height(), 1.0);
+    std::vector<CurvePoint> points = currentPoints();
+    // On a point, that point; the first of equals.
+    std::optional<size_t> near;
+    for (size_t index = 0; index < points.size(); ++index)
+        if (!near || std::hypot(points[index].x - x, points[index].y - y) < std::hypot(points[*near].x - x, points[*near].y - y))
+            near = index;
+    if (near && std::hypot(points[*near].x - x, points[*near].y - y) < 0.055) {
+        m_selectedPoint = near;
+        return Drag{.kind = Drag::Kind::point, .index = *near, .from = at};
+    }
+    // Else a new point; the ends bound its x.
+    if (points.size() >= 16 || !std::all_of(points.begin(), points.end(), [x](const CurvePoint &each) { return std::abs(each.x - x) > 0.01; }))
+        return std::nullopt;
+    const CurvePoint point{x, y};
+    points.push_back(point);
+    std::stable_sort(points.begin(), points.end(), [](const CurvePoint &left, const CurvePoint &right) { return left.x < right.x; });
+    store(points);
+    const size_t index = size_t(std::find(points.begin(), points.end(), point) - points.begin());
+    m_selectedPoint = index;
+    return Drag{.kind = Drag::Kind::point, .index = index, .from = at};
+}
+
+void CameraRawCurveControls::beginDrag(QPointF at, QSizeF size)
+{
+    // Qt may lose a release: every press picks afresh.
+    const bool parametric = !m_session.filterEdit() || m_session.filterEdit()->rawPanel.curvePage == CameraRawCurvePage::parametric;
+    m_drag = parametric ? parametricDrag(at, size) : pointDrag(at, size);
+    continueDrag(at, size);
+}
+
+void CameraRawCurveControls::continueDrag(QPointF at, QSizeF size)
+{
+    if (!m_drag)
+        return;
+    const double x = at.x() / std::max(size.width(), 1.0), y = 1 - at.y() / std::max(size.height(), 1.0);
+    const Drag drag = *m_drag;
+    switch (drag.kind) {
+    case Drag::Kind::point: {
+        std::vector<CurvePoint> points = currentPoints();
+        if (drag.index >= points.size())
+            return;
+        points[drag.index].y = y;
+        // Ends stay ends; the rest keep their order.
+        if (drag.index > 0 && drag.index < points.size() - 1)
+            points[drag.index].x = std::min(points[drag.index + 1].x - 0.01, std::max(points[drag.index - 1].x + 0.01, x));
+        store(points);
+        return;
+    }
+    case Drag::Kind::divider: {
+        const double value = x * 100;
+        update([&drag, value](CameraRawSettings &settings) {
+            // Below the next divider; normalizing does the rest.
+            CameraRawCurveSettings &curve = settings.curve;
+            if (drag.index == 0)
+                curve.shadowSplit = std::min(value, curve.darkSplit - 2);
+            else if (drag.index == 1)
+                curve.darkSplit = std::min(curve.lightSplit - 2, value);
+            else
+                curve.lightSplit = value;
+        });
+        return;
+    }
+    case Drag::Kind::region: {
+        const double amount = std::min(100.0, std::max(-100.0, drag.start - (at.y() - drag.from.y()) / std::max(size.height(), 1.0) * 200));
+        update([&drag, amount](CameraRawSettings &settings) { settings.curve.*drag.key = std::round(amount); });
+        return;
+    }
+    }
+}
+
+void CameraRawCurveControls::removePoint(QPointF at, QSizeF size)
+{
+    std::vector<CurvePoint> points = currentPoints();
+    const double x = at.x() / size.width();
+    // The nearest inner point by x, within 0.04; ends stay.
+    std::optional<size_t> nearest;
+    for (size_t index = 1; index + 1 < points.size(); ++index)
+        if (!nearest || std::abs(points[index].x - x) < std::abs(points[*nearest].x - x))
+            nearest = index;
+    if (!nearest || !(std::abs(points[*nearest].x - x) < 0.04))
+        return;
+    points.erase(points.begin() + std::ptrdiff_t(*nearest));
+    m_selectedPoint.reset();
+    store(points);
+}